U.S. patent number 11,365,123 [Application Number 16/639,805] was granted by the patent office on 2022-06-21 for method for producing graphene nanospheres.
This patent grant is currently assigned to KOREA UNIVERSITY OF TECHNOLOGY AND EDUCATION INDUSTRY-UNIVERSITY COOPERATION FOUNDATION. The grantee listed for this patent is KOREA UNIVERSITY OF TECHNOLOGY AND EDUCATION INDUSTRY-UNIVERSITY COOPERATION FOUNDATION. Invention is credited to Soon Mok Choi, Byeong-Geun Kim.
United States Patent |
11,365,123 |
Choi , et al. |
June 21, 2022 |
Method for producing graphene nanospheres
Abstract
The present invention provides a method of manufacturing a
graphene nanosphere through a single process that is simplified in
order to enable mass production. The method includes step 1 of
manufacturing a silicon carbide nanosphere coated with graphene
through chemical vapor deposition (CVD) using a gas containing a
silicon source and a carbon source and step 2 of discontinuing the
chemical vapor deposition (CVD) and then performing cooling.
Inventors: |
Choi; Soon Mok (Cheonan-si,
KR), Kim; Byeong-Geun (Seongnam-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
KOREA UNIVERSITY OF TECHNOLOGY AND EDUCATION INDUSTRY-UNIVERSITY
COOPERATION FOUNDATION |
Cheonan-si |
N/A |
KR |
|
|
Assignee: |
KOREA UNIVERSITY OF TECHNOLOGY AND
EDUCATION INDUSTRY-UNIVERSITY COOPERATION FOUNDATION
(Cheonan-si, KR)
|
Family
ID: |
1000006382182 |
Appl.
No.: |
16/639,805 |
Filed: |
August 16, 2018 |
PCT
Filed: |
August 16, 2018 |
PCT No.: |
PCT/KR2018/009402 |
371(c)(1),(2),(4) Date: |
February 18, 2020 |
PCT
Pub. No.: |
WO2019/035663 |
PCT
Pub. Date: |
February 21, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20200247677 A1 |
Aug 6, 2020 |
|
Foreign Application Priority Data
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|
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Aug 18, 2017 [KR] |
|
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10-2017-0104852 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C
16/26 (20130101); C01B 32/186 (20170801); C01P
2004/64 (20130101); C01P 2004/04 (20130101); C01P
2002/82 (20130101); C01P 2004/03 (20130101); C01P
2002/72 (20130101); C01P 2002/85 (20130101); C01P
2004/34 (20130101) |
Current International
Class: |
C01B
32/186 (20170101); C23C 16/26 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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106219523 |
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Dec 2016 |
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CN |
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10-2004-0101858 |
|
Dec 2004 |
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KR |
|
10-0596291 |
|
Jul 2006 |
|
KR |
|
10-1452397 |
|
Oct 2014 |
|
KR |
|
10-1486760 |
|
Jan 2015 |
|
KR |
|
2015/010230 |
|
Jan 2015 |
|
WO |
|
Other References
Jeanne N'diaye et al., "One-Step In-Situ Growth of Core-Shell
SiC@Graphene Nanoparticles/Graphene Hybrids by Chemical Vapor
Deposition", Advanced Materials Interfaces, 2016, 6 pages, vol. 3,
No. 81500806. (Year: 2016). cited by examiner .
Kim et al; "One-step growth of multilayer-graphene hollow
nanospheres via the self-elimination of SiC nuclei templates",
Scientific Reports, Oct. 23, 20217, vol. 7, 13774. (Year: 2017).
cited by examiner .
Jeanne N'diaye et al., "One-Step In-Situ Growth of Core-Shell
SiC@Graphene Nanoparticles/Graphene Hybrids by Chemical Vapor
Deposition", Advanced Materials Interfaces, 2016, 6 pages, vol. 3,
No. 8 1500806. cited by applicant .
Hao Zhuang et al., "Graphene/3C-SiC Hybrid Nanolaminate", ACS
Applied Materials & Interfaces, 2015, 42 pages, vol. 7, No. 51.
cited by applicant .
Tao Chen et al., "Macroscopic Graphene Fibers Directly Assembled
from CVD-Grown Fiber-Shaped Hollow Graphene Tubes", Angewandte
Chemie, 2015, pp. 15160-15163, vol. 127. cited by applicant .
Byeong Geun Kim et al., "One-step Growth of Multilayer-graphene
Hollow Nanospheres via the Self-elimination of SiC Nuclei
Templates", Scientific Reports, Oct. 23, 2017, 8 pages, vol. 7,
13774. cited by applicant .
International Search Report for PCT/KR2018/009402 dated Dec. 18,
2018 [PCT/ISA/210]. cited by applicant.
|
Primary Examiner: Wieczorek; Michael P
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
The invention claimed is:
1. A method of manufacturing a graphene nanosphere, comprising:
step 1 of manufacturing a silicon carbide nanosphere coated with
graphene through chemical vapor deposition (CVD) using a gas
containing a silicon source and a carbon source, and step 2 of
discontinuing the chemical vapor deposition (CVD) and then
performing cooling to form the graphene nanosphere.
2. The method of claim 1, wherein the silicon source and the carbon
source are a single gas containing silicon and carbon.
3. The method of claim 1, wherein the step 1 is performed at a
temperature of 1000 to 3000.degree. C. under a pressure of 100 to
760 torr.
4. The method of claim 3, wherein the step 1 is performed at a
temperature of 1000 to less than 2000.degree. C.
5. The method of claim 4, wherein the graphene nanosphere comprises
a silicon carbide nanocrystal core and a graphene coating layer
formed on the core.
6. The method of claim 1, wherein the step 1 is performed at a
temperature of 2000 to 3000.degree. C.
7. The method of claim 6, wherein the graphene nanosphere is a
hollow graphene nanosphere.
8. The method of claim 1, wherein the step 1 comprises supplying a
gas containing a carrier gas.
9. The method of claim 8, wherein in the step 1, a flow rate ratio
of (carrier gas)/(silicon source and carbon source) is 10 to 1000.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a National Stage of International Application
No. PCT/KR2018/009402 filed Aug. 16, 2018, claiming priority based
on Korean Patent Application No. 10-2017-0104852 filed Aug. 18,
2017, the entire disclosures of which are incorporated herein by
reference.
TECHNICAL FIELD
The present invention relates to a method of manufacturing a
graphene nanosphere, and more particularly to a method of
manufacturing a graphene nanosphere using a single chemical vapor
deposition (CVD) process.
BACKGROUND ART
In the future, graphene is expected to be utilized in a very wide
range of industries, including those of semiconductor materials and
devices, energy storage and conversion systems, transparent
electrodes, functional composite materials, heat-dissipating
materials, barrier coatings, printed electronics, and the like, due
to the superior physical and chemical properties thereof.
Nanostructures such as nanowires or nanotubes are very useful in a
variety of fields because of the small nano-scale sizes, high
surface areas, shapes and the like thereof. In the case of
graphene, research into application thereof in various fields such
as those of electronics, biotechnology, etc. is being actively
conducted these days by artificially changing the structure, shape
or the like of graphene.
In accordance with the rapid development of IT technology, a
drastic increase in the demand of advanced electronic devices such
as smartphones is required in order to develop high-density
high-power next-generation energy storage systems, and thus
thorough research related to secondary batteries and capacitors is
currently ongoing.
In order to develop a battery of high density/high power, it is
necessary to develop an electrode material having a high specific
capacitance and an electrolyte having a wide potential window.
Hollow graphene nanospheres, in particular, have a large surface
area, high electrical conductivity, and superior physical and
chemical properties, and are receiving a great deal of attention as
an ideal alternative to supercapacitor electrode materials.
Methods of manufacturing hollow graphene nanospheres that have been
developed to date include joule heating, laser processing,
high-temperature carbonization and solution methods, and mostly use
templates such as metal particles. For example, Korean Patent No.
10-1452397 discloses a method of manufacturing hollow graphene
particles having high air permeability using a capillary molding
phenomenon during pyrolysis of polymer particles through the
addition of a colloidal solution.
The method using the template has the advantage of producing
reproducible graphene nanospheres, but is disadvantageous in that
the metal particles used as the template must be removed in a
subsequent process.
Therefore, with the goal of realizing technical commercialization,
it is necessary to simplify processing in order to enable mass
production and efficient production.
CITATION LIST
Patent Literature
1. Korean Patent No. 10-1452397
DISCLOSURE
Technical Problem
An objective of the present invention is to provide a method of
manufacturing a graphene nanosphere through a single process that
is simplified in order to enable mass production.
Technical Solution
In order to accomplish the above objective, the present invention
provides a method of manufacturing a graphene nanosphere including
step 1 of manufacturing a silicon carbide nanosphere coated with
graphene through chemical vapor deposition (CVD) using a gas
containing a silicon source and a carbon source, and step 2 of
discontinuing the chemical vapor deposition (CVD) and then
performing cooling.
In the method of manufacturing the graphene nanosphere according to
an embodiment of the present invention, the silicon source and the
carbon source may be a single gas containing silicon and
carbon.
In the method of manufacturing the graphene nanosphere according to
an embodiment of the present invention, step 1 may be performed at
a temperature of 1000 to 3000.degree. C. under a pressure of 100 to
760 torr.
In the method of manufacturing the graphene nanosphere according to
an embodiment of the present invention, step 1 may be performed at
a temperature of 1000 to less than 2000.degree. C.
In the method of manufacturing the graphene nanosphere according to
an embodiment of the present invention, the graphene nanosphere may
include a silicon carbide nanocrystal core and a graphene coating
layer formed on the core.
In the method of manufacturing the graphene nanosphere according to
an embodiment of the present invention, step 1 may be performed at
a temperature of 2000 to 3000.degree. C.
In the method of manufacturing the graphene nanosphere according to
an embodiment of the present invention, the graphene nanosphere may
be a hollow graphene nanosphere.
In the method of manufacturing the graphene nanosphere according to
an embodiment of the present invention, step 1 may include
supplying a gas containing a carrier gas.
In the method of manufacturing the graphene nanosphere according to
an embodiment of the present invention, a flow rate ratio of
(carrier gas)/(silicon source and carbon source) in step 1 may be
10 to 1000.
In addition, the present invention provides a graphene nanosphere
manufactured through a single chemical vapor deposition (CVD)
process.
Advantageous Effects
According to the present invention, a graphene nanosphere can be
manufactured through a single process that is simplified in order
to enable mass production. Moreover, processing conditions are
controlled, thus enabling the manufacture of a hollow graphene
nanosphere and a graphene nanosphere having a silicon carbide
nanocrystal core therein. The graphene nanosphere thus manufactured
can be widely used in the development of supercapacitors, lithium
batteries, structural reinforcement materials, catalyst supports,
etc. because of the superior mechanical and electrical properties
of graphene.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 schematically shows a process of manufacturing a graphene
nanosphere using chemical vapor deposition according to the present
invention;
FIG. 2 shows (a) a scanning electron microscope (SEM) image and (b)
and (c) transmission electron microscope (TEM) images of the hollow
graphene nanospheres manufactured in Example 1 of the present
invention;
FIG. 3 shows (a) an XRD graph and (b) a Raman spectrum of the
hollow graphene nanospheres manufactured in Example 1 of the
present invention;
FIG. 4 shows (a) a TEM image and the results of energy-dispersive
spectroscopy (EDS) and (b) a Raman spectrum of the graphene
nanospheres manufactured in Example 2 of the present invention;
and
FIG. 5 shows (a) a SEM image, (b) an EDS spectrum and (c) a TEM
image of the graphene nanospheres manufactured in Example 3 of the
present invention.
MODE FOR INVENTION
Hereinafter, a detailed description will be given of the present
invention.
The present invention pertains to a method of manufacturing a
graphene nanosphere through a process that is simplified in order
to enable mass production. According to the present invention, a
graphene nanosphere may be manufactured using a single chemical
vapor deposition (CVD) process, and by controlling the processing
conditions, a hollow graphene nanosphere and a graphene nanosphere
having a silicon carbide nanocrystal core therein may be
selectively manufactured.
The method of manufacturing the graphene nanosphere according to
the present invention includes step 1 of manufacturing a silicon
carbide nanosphere coated with graphene through chemical vapor
deposition (CVD) using a gas containing a silicon source and a
carbon source and step 2 of discontinuing the chemical vapor
deposition (CVD) and then performing cooling.
FIG. 1 schematically shows the process of manufacturing the
graphene nanosphere according to the present invention. With
reference to FIG. 1, individual steps are described below.
Specifically, a silicon carbide nanosphere coated with graphene is
manufactured through chemical vapor deposition (CVD) using a gas
containing a silicon source and a carbon source (step 1).
With reference to FIG. 1, the silicon source and the carbon source,
which are precursors, are placed together with a carrier gas such
as hydrogen in a chemical vapor deposition reactor (in FIG. 1, step
i)), after which the precursors are pyrolyzed using heat energy at
a high temperature, thus forming a silicon carbide (SiC)
nanocrystal having a size of less than 15 nm (in FIG. 1, step
ii)).
Thereafter, a carbon (C) solid phase is formed on the surface of
the silicon carbide (SiC) nanocrystal (in FIG. 1, step iii)), and
the carbon (C) solid phase is rearranged to thus form graphene
having a layered structure (in FIG. 1, step iv)), and this layered
structure prevents the internal supply of the source for growing
the silicon carbide (SiC) nanocrystal. Accordingly, after step iv)
of FIG. 1, the silicon carbide (SiC) nanocrystal may not grow.
Here, the silicon source and the carbon source may be used in the
form of a single gas containing silicon (Si) and carbon (C), and
examples thereof may include, but are not limited to,
trichlorosilane, tetramethylsilane, methyltrichlorosilane and the
like.
Also, the silicon source and the carbon source may be used
separately, and the silicon source may include silicon-containing
gas, such as silane (SiH.sub.4) gas or disilane (Si.sub.2H.sub.6)
gas.
The carbon source may be any one selected from the group consisting
of carbon monoxide, carbon dioxide, methane, ethane, ethylene,
ethanol, acetylene, propane, propylene, butane, butylene,
butadiene, pentane, pentene, pentyne, pentadiene, cyclopentane,
cyclopentadiene, hexane, hexene, cyclohexane, cyclohexadiene,
benzene, toluene and combinations thereof.
The carrier gas, which is used together with the silicon source and
the carbon source, may be selected from the group consisting of
hydrogen (H.sub.2), argon (Ar), nitrogen (N.sub.2) and combinations
thereof.
In the method of manufacturing the graphene nanosphere according to
an embodiment of the present invention, the carrier gas and the
silicon source and carbon source may be supplied at a flow rate
ratio ((flow rate (cc/min) of carrier gas)/(flow rate (cc/min) of
silicon source and carbon source)) of 10-2000. For example, H.sub.2
and tetramethylsilane may be supplied at a constant flow rate ratio
of 100-500.
The chemical vapor deposition may be carried out under constant
conditions of a temperature of 1000 to 3000.degree. C. and a
reactor chamber pressure of 100 to 760 torr.
In the present invention, the inner temperature of the reactor has
to be set within an appropriate temperature range in order to form
a silicon carbide nanocrystal seed for the graphene nanosphere and
to pyrolyze the silicon carbide nanocrystal covered with a carbon
solid phase into a silicon gas phase and a carbon solid phase.
For example, when the temperature is set in the range of 1000 to
less than 2000.degree. C., the silicon carbide nanocrystal covered
with a carbon solid phase is not sufficiently pyrolyzed into a
silicon gas phase and a carbon solid phase, thus obtaining a
graphene nanosphere having a silicon carbide nanocrystal core and a
graphene coating layer formed on the core.
In another example, when the temperature is set in the range of
2000 to 3000.degree. C., the carbide nanocrystal covered with a
carbon solid phase is sufficiently pyrolyzed into a silicon gas
phase and a carbon solid phase, thus obtaining a graphene
nanosphere, the inside of which is empty, that is, a hollow
graphene nanosphere.
Next, the chemical vapor deposition is discontinued and then
cooling is performed (step 2).
Here, the cooling process is preferably performed through furnace
cooling in order to manufacture a nanosphere or a hollow nanosphere
having high graphene crystallinity by appropriately pyrolyzing the
silicon carbide (SiC) nanocrystal using heat energy applied during
chemical vapor deposition.
With reference to FIG. 1, the silicon carbide (SiC) nanocrystal
covered with the carbon (C) solid phase is removed while being
pyrolyzed into a silicon (Si) gas phase and a carbon (C) solid
phase using high-temperature heat energy without source supply.
During furnace cooling to a low temperature from a high temperature
after discontinuing the source supply, additional pyrolysis of SiC
nanocrystals occurs. The furnace cooling may be conducted at a
cooling rate of 5 to 15.degree. C./min. Among pyrolyzed elements,
silicon (Si) has high vapor pressure compared to carbon (C), and
the melting point thereof is relatively low, and thus silicon (Si)
in a gas phase is released from between the layers of the carbon
(C) solid phase (in FIG. 1, step v)).
Thereafter, the silicon carbide (SiC) nanocrystal is completely
decomposed, and rearrangement of the carbon (C) solid phase
continues to thus complete the layered structure, thereby forming a
graphene nanosphere, the inside of which is empty, namely a hollow
graphene sphere (in FIG. 1, step vi)).
According to the present invention, it is possible to efficiently
and economically manufacture a graphene nanosphere through a single
process, unlike a conventional method of manufacturing a graphene
nanosphere.
The graphene nanosphere, composed of the core including the silicon
carbide (SiC) nanocrystal and the graphene layer formed on the
core, may exhibit superior mechanical properties and may thus be
utilized as a structural reinforcement material, and the hollow
graphene sphere may be applied to supercapacitors, lithium
batteries, catalyst supports, etc.
A better understanding of the present invention will be given
through preferred examples and test examples. The following
examples and test examples are merely set forth to more clearly
express the present invention, but are not to be construed as
limiting the scope of the present invention.
EXAMPLE 1
Hydrogen gas and tetramethylsilane (TMS) were placed at a flow rate
ratio of H.sub.2/TMS of 320 in a reactor, heated under a pressure
of 550 torr, reacted for 1 hr at a maximum temperature of
2100.degree. C., and then cooled to room temperature.
FIG. 2 shows (a) a scanning electron microscope (SEM) image and (b)
and (c) transmission electron microscope (TEM) images of the hollow
graphene nanospheres manufactured in Example 1 of the present
invention. With reference to FIG. 2, it can be seen that the hollow
graphene nanospheres had a spherical shape ((a)) and that the
spherical graphene nanospheres were hollow ((b), (c)). As is
apparent from the high-resolution transmission electron microscope
(HRTEM) image in (b) of FIG. 2, graphene had a layered structure.
With reference to FIG. 2, it can be confirmed that the hollow
graphene nanospheres had an inner diameter of 20 to 30 nm.
FIG. 3 shows (a) an XRD graph and (b) a Raman spectrum of the
hollow graphene nanospheres manufactured in Example 1 of the
present invention. As shown in FIG. 3, the hollow graphene spheres
of Example 1 can be confirmed to be graphitic carbon having few
defects and good crystallinity. Moreover, despite the use of both
the silicon source and the carbon source, it can be confirmed that
the phase related to silicon (Si) or silicon carbide (SiC) was
absent.
In Example 1, 100% of the reaction product was hollow graphene
nanospheres.
EXAMPLE 2
The present example was performed in the same manner as in Example
1, with the exception that the maximum temperature was set to
1500.degree. C.
FIG. 4 shows (a) a TEM image and the results of energy-dispersive
spectroscopy (EDS) and (b) a Raman spectrum of the graphene
nanospheres manufactured in Example 2 of the present invention.
With reference to FIG. 4, in the graphene nanospheres produced at a
low temperature of 1500.degree. C., particles in which the insides
of the graphene nanospheres were filled with silicon carbide (SiC)
nanocrystal were observed, unlike the hollow graphene nanospheres
of Example 1 manufactured at 2100.degree. C.
In Example 2, 60% of the reaction product was hollow graphene
nanospheres, and the remaining 40% was graphene nanospheres, the
insides of which were filled.
EXAMPLE 3
The present example was performed in the same manner as in Example
1, with the exception that the maximum temperature was set to
1900.degree. C.
FIG. 5 shows (a) a SEM image, (b) an EDS spectrum and (c) a TEM
image of the graphene nanospheres manufactured in Example 3 of the
present invention. With reference to FIG. 5, in the graphene
nanospheres produced at a temperature of 1900.degree. C., the
number of hollow graphene nanospheres was significantly increased,
unlike the graphene nanospheres of Example 2 manufactured at
1500.degree. C. As shown in FIG. 5, the inner diameter of the
hollow graphene nanospheres was 20 to 30 nm.
In Example 3, 80% of the reaction product was hollow graphene
nanospheres, and the remaining 20% was graphene nanospheres, the
insides of which were filled.
The technical spirit of the present invention described above is
not limited to the aforementioned embodiments and the appended
drawings, and those skilled in the art will appreciate that various
modifications, additions and substitutions are possible, without
departing from the scope and spirit of the invention as disclosed
in the accompanying claims.
* * * * *